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  • Antibiotics  (2)
  • Cyclodextrins  (2)
  • 2,8-dimethyl-1,7-dioxaspiro[5.5]undecane  (1)
  • 2-phenylbutyric acid  (1)
  • 1990-1994  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Andrena wilkella male bees discriminate between enantiomers of cephalic secretion components (1990)
    Springer
    Journal of chemical ecology 16 (1990), S. 429-441 
    Details
    ISSN: 1573-1561
    Keywords: Enantiomer discrimination ; male patrolling ; odor marking ; Hymenoptera ; Apoidea ; Andrena wilkella ; bee ; EAG ; spiroacetal ; absolute configuration ; 2,8-dimethyl-1,7-dioxaspiro[5.5]undecane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Diastereomers of the spiroacetal, 2,8-dimethyl-1,7-dioxaspiro [5.5]undecane, represent main components of the cephalic secretion from males of the solitary bee,Andrena wilkella. The major compound proved to be of high enantiomeric purity, showing (2S,6R,8S) configuration. Only the naturally occurring enantiomer attracted patrolling males in the field; its antipode was behaviorally inactive and in a racemic mixture did not inhibit response. The (E,Z) diastereomers were also found to be almost inactive. EAG studies gave the same result as the behavioral tests. The biological function of the spiroacetal is discussed in view of the evolution of the mating behavior inA. wilkella.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01021775
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of the absolute configuration of secondary alcohols with Horeau's method including enantioselective gas chromatography (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 6 (1994), S. 141-147 
    Details
    ISSN: 0899-0042
    Keywords: Horeau's method ; configuration of secondary alcohols ; enantioselective gas chromatography ; 2-phenylbutyric acid ; cyclodextrin derivative ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of optically active secondary alcohols with excess of racemic 2-phenylbutyric acid anhydride in pyridine proceeds at different rates to the diastereoisomeric esters (kinetic partial resolution). According to Horeau the (unknown) absolute configuration of the alcohol can be derived from the optical rotation of the remaining excess of 2-phenylbutyric acid in the reaction mixture. Measuring the optical rotation may be very difficult in cases of small absolute rotation values and may be inaccurate due to the necessity to completely remove all chiral impurities. The application of Horeau's method is greatly facilitated by gas chromatographic determination of the enantiomeric ratio of the remaining 2-phenylbutyric acid after methylation using a short capillary column with heptakis(2,6-di-O-methyl-3-O-pentyl)-β-cyclodextrin as a chiral stationary phase. Baseline resolution of the enantiomers is achieved after approximately 10 min of retention time. Due to the high selectivity of capillary gas chromatography the probability of impurities in the mixture to interfere with the measurement of the enantiomeric ratio is extremely low. © 1994 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530060215
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  • 3
    Electronic Resource
    Electronic Resource
    What is the Structure of Peptide Antibiotic Tü 1718 B? Previously Proposed Structure Disproved by Synthesis (1992)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1992 (1992), S. 1281-1287 
    Details
    ISSN: 0170-2041
    Keywords: N-Valyl-dihydroxyhomoproline ; Streptomyces antibioticus ssp. Tü 1718 B ; Antibiotics ; Peptides ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two stereoisomers (1a and 1b) of N-(L-valyl)-2′,5-dihydroxyhomoproline, the proposed structure of the dipeptide antibiotic Tü 1718 B, were synthesized by starting from natural (2S,4R)-hydroxyproline. The 1H- and 13C-NMR spectra of 1a and 1b clearly differ from the corresponding spectra of the natural product. From both synthetic stereoisomers characteristic mass spectra were obtained after esterification and trifluoroacetylation. Isomer 1a is present as a mixture of two stable conformers, as indicated by peak splitting in the1H-NMR spectra, which disappears at higher temperature, while 1b exits as a single conformer. Both synthetic stereoisomers are antibiotically inactive.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1992199201212
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis of (3R,4R)-3-Amino-4-hydroxyhexahydroazepine, the Chiral Constituent of the Antibiotic Ophiocordin (1993)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 651-655 
    Details
    ISSN: 0170-2041
    Keywords: 3-Amino-4-hydroxyhexahydroazepine ; Cordyceps ophioglossoides ; Antifungals ; Antibiotics ; Ophiocordin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (3R,4R)-3-Amino-4-hydroxyhexahydroazepine (2), the optically active constituent of the antifungal antibiotic ophiocordin (1), was prepared in a multistep synthesis starting from D-serine. The absolute configuration was unambigously assigned by a comparison of the synthesized stereoisomer 2 with its racemate and the chiral moiety of the antibiotic ophiocordin by enantioselective gas chromatography.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1993199301106
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  • 5
    Electronic Resource
    Electronic Resource
    Cyclodextrins as chiral stationary phases in capillary gas chromatography. Part VII: Cyclodextrins with an inverse substitution pattern - synthesis and enantioselectivityPart VI, see reference [6]. (1990)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 13 (1990), S. 702-707 
    Details
    ISSN: 0935-6304
    Keywords: Enantioselective capillary gas chromatography ; Cyclodextrins ; Inverse substitution pattern ; Mechanism of chiral recognition ; Applications ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transferring the site of specific substitution of dipentylated cyclodextrins with methyl or acyl residues from the secondary 3-hydroxyl group to the primary 6-hydroxyl group was expected to provide new information on the mechanism of chiral recognition. The 3-position points towards and the 6-position points away from the cyclodextrin cavity which via inclusion complex formation is supposed to play a major role in chiral separation. The “inverse” 6-O-acyl-2,3-di-O-pentyl-cyclodextrins displayed almost no enantioselectivity but the corresponding 6-O-methyl derivatives are a versatile supplement to the chiral capillary GC phases nowadays available. Among the compounds that could be enantiomerically resolved are alcohols, amino acids, alkyl halides, bicyclic ethers, acetals, olefins, other hydrocarbons and chiral pharmaceuticals.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240131010
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  • 6
    Electronic Resource
    Electronic Resource
    A Molecular-Dynamics Simulation of the Complex Formation between Methyl (R)/(S)-2-Chloropropionate and Heptakis(3-O-acetyl-2,6-di-O-pentyl)-β-cyclodextrin (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 119-126 
    Details
    ISSN: 0009-2940
    Keywords: Host-guest complexes ; Molecular-dynamics (MD) simulation ; Enantioselective gas chromatography ; Cyclodextrins ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The energies of complexation of methyl (R)/(S)-2-chloropropionate [(R)/(S)-2] with heptakis(3-O-acetyl-2,6-di-O-pentyl)-β-cyclodextrin (1) and the structures of the corresponding complexes were determined by molecular-dynamcis (MD) simulations at 300 and 333 K. The geometry of the complexes, the conformations of complexed and uncomplexed 1 and (R)/(S)-2 and the closest H-H distances between host and guest in the complexes were determined from the trajectories. The results correspond to the experimental findings from enantioselective gas chromatography.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270120
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